<?php
class Mwc_SystemPoint_Block_Userpoint_Render_Group extends Mage_Adminhtml_Block_Abstract implements Varien_Data_Form_Element_Renderer_Interface {
  public function render(Varien_Data_Form_Element_Abstract $element) {
    //You can write html for your button here
    $html = '
    <table cellspacing="0" class="form-list">
    <tbody>
    <tr>
        <td class="label">
        	<label for="group_title">Group name</label>
        </td>
	    <td class="value">
	        <input type="text" class=" input-text" title="Group name" value="" name="group_title" id="group_title">            
	    </td>
    </tr>
    </tbody></table>';
   $html .= "<script language='JavaScript'>
		function changeDiv(val) { 
			document.getElementById(0).style.display = 'none'; 			
			document.getElementById(1).style.display = 'none'; 		
			document.getElementById(val).style.display = 'block'; 
		} 
   </script>";
   return $html;
  }
}